Inboard strike-off blade actuating mechanism

ABSTRACT

An actuating mechanism for the strike-off blade of a selfloading scraper where the blade, hinged on the rolling bottom door, is raised and lowered by cam elements inboard of the scraper side walls as the door is moved.

ilnin Swies Paiem 119 Whitworth 1 51 May 15, 1973 [54] INBOARD STRIKE-OFF BLADE [56] References Cited ACTUATING MECHANISM UNITED STATES PATENTS [75] Inventor: Frank whitwm'th Lubbock 2,988,832 6/1961 Hancock et a]. .137/8 3,660,914 5 1972 Bechman et a! ..37 129 Assignee: Clark Eqflipmem Company Primary Examiner-Robert E. Pulfrey Buchanan Assistant ExaminerEugene H. Eickholt [22] Filed: Oct. 4, 1971 Attorney Kenneth C. Witt et al.

[21] App]. No.: 186,135 [57] ABSTRACT An actuating mechanism for the strike-off blade of a [52] US. Cl ..37/l24, 37/129 'selflloading craper where the blade, hinged on [he [51] Int. Cl. ..E02f 5/00 rolling bottom door is raised and |owered by cam [58] Field of Search ..37/4, 8, l24-l 29 ments inboard of the scraper side walls as the door is moved.

5 Claims, 3 Drawing Figures PATENTEWS'Q 3,732,637

I N VEN TOR 35 FRANKA D. WHITWORTH BY 40k.

ATTORNEY INBOARD STRIKE-OFF BLADE ACTUATING MECHANISM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to the art of earth moving apparatus and more particularly to tractor scrapers of the self-loading type, i.e., an elevator mechanism is used to assist in loading earth material into the scraper bowl. Owing to the position of the elevator mechanism earth material is dumped or ejected through an opening in the bottom of the scraper bowl. A rear end gate pushes forward to eject the earth material through the opening normally covered by a rolling bottom door. Hinged on the front door is a strike-off blade which pivots to an inclined position as the door is opened, leveling and spreading the dumped earth material. The present invention pertains to an actuating mechanism for the strike-off blade.

2. Description of the Prior Art It is known to actuate the strike-off blade by means of camming rollers mounted on the outer sides of the scraper side walls. For example, see U.S. Pat. No. 2,988,832 where a pair of striker plates secured to the opposite ends of the strike-off blade travel longitudinally outboard of the scraper side walls and engage the rollers as the door moves. As the door is closed, the strike-off blade is rotated upwardly adjacent a fixed support structure holding the main blade, closing the space in front of the door. While the actuating mechanism is simple and has proved highly satisfactory, it has certain inherent disadvantages.

For instance, the camming rollers and striker plates are located outboard of the scraper side walls. Consequently, these parts are exposed to heavy objects such as large boulders and subject to being bent or broken.

Also, the support structure of the main blade and the leading edge of the strike-off blade are normally in contact or sufficiently close that there is no problem with the loss of earth material between the two, however, as

the cam rollers and striker plates become worn in service there is a tendency for a gap to form requiring the use of shims or weld build-ups of the camming surfaces to prevent excessive material loss.

SUMMARY OF THE INVENTION A strike-off blade actuating mechanism is provided entirely inboard of the scraper side walls. Cam elements, one secured on the inner side of one side wall and the other mounted diametrically opposite on the other side wall engage a pair of camming surfaces, one on each end of the strike-off blade, traveling with the blade inboard of the scraper side walls. Cam actuation is such that the blade is, hinged up, as the door moves to close and pivots down to spread the dumped earth material as the door opens.

Preferably the camming relationship is such as to cause the leading edge of the strike-off blade to travel in an arcuate and then rectilinear path bringing the blade edge up to a level above the stationary support structure of the main blade.

As, another feature of the invention, the cam elements may have replaceable cam sections which permit removal of worn cam sections and replacement with new sections for restoring normal cam actuation.

Inboard mounting of the actuating mechanism provides protection from the more extreme wear condition encountered in normal scraper service. Further, with the preferred embodiment of the invention, the leading edge of the strike-off blade is caused to move in a path bringing it up behind and forwardly over the main blade support structure, thus insuring, in the closed position of the door, that any drop in the blade owing to cam wear is limited by contact with the main blade support structure. Thus, instead of a wider gap developing between the edge of the blade and main blade support structure, any gap is narrowed or becomes nonexistent as cam wear occurs. Also, the provision of replaceable cam sections makes repairs less costly, decreases down time and improves the service life of other parts.

Other advantages of the invention will become apparent by reference to the following detailed description of the preferred embodiment which proceeds with a description of the drawings;

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a tractor and selfloading scraper unit having a rolling door dumping arrangement suitable for employing the invention;

FIG. 2 is a partial sectional view showing the scraper main blade, the strike-off blade, and cam arrangement, according to the preferred embodiment of the invention, for actuating the strike-off blade where the latter is depicted raised in full lines and lowered in dot-dash lines; and

FIG. 3 is a fragmentary perspective view of the rolling door and strike-off blade with portions of the scraper side walls and floor broken away.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 depicts an earth moving apparatus or more specifically, a self-loading scraper 10 towed by tractor 12. The scraper 10 has a yoke 13 pivotally connected at 14 to the tractor to permit articulation. Arms 15 pivotally connect the scraper bowl 16 such that it may be lowered and raised by action of lift cylinders 17, one adjacent each side of the scraper. A fixed main blade 18 is rigidly mounted on a blade support structure 19 extending across the front between the side 25 of the bowl 16. The blade 18 has a downward inclination suitable for engagement with the ground when the scraper bowl 16 is lowered for making a cut. An elevator 20 is mounted in front of the bowl 16 to break loose the earth material in advance of the main blade 18 and assists in filling the bowl in a known manner. The bowl 16 is supported at the rear on ground engaging wheels 21 mounted on an axle which is supported on a trailing sub-frame assembly 22. An end gate 24 extends across the back of the scraper bowl between the side walls 25 and slides on a fixed floor portion 26. A rolling door 27 is suspended at each end on rollers 28 below the fixed floor portion 26. The rollers 28 travel in longitudinal trackways, 29 on each side of the scraper bowl. An ejection mechanism 30 supported on the sub-frame assembly 22 is actuated to retract the door 27 and push the end gate 24 forwardly to expel the earth material through an opening in the floor which is covered by the door 27 when it is in the forwardmost position as shown in FIG. 1. A strike-off blade 32 is hinged on the front of the door 27 and pivots downwardly as the door retracts to spread or level the earth material beneath the scraper as it moves forwardly dumping the load as it goes.

More specifically, with reference to FIGS. 2 and 3, the strike-off blade 32 is hinged at 34 to the door 27 and has secured at each end thereof an end plate 35 which travels with the blade following a path closely parallel and inboard of the scraper side walls 25. An extension 36 on each plate 35 has an upper straight surface 38.

A pair of cam blocks 40, one secured on the inboard side of one side wall 25 and the other secured diametrically opposite on the other side wall 25 each has a fixedly mounted section 41 and a removable section 42 attached to the section 41 by bolts 43. Each cam section 42 has a straight surface 44 which extends generally parallel to the direction of movement of the door 27 and at a level above the floor such that mutual sliding contact is made with the surfaces 38 as the blade moves fore and aft with the door. A radius 45 on each cam block faces toward the rear of the scraper bowl and initiates the pivotal movement of the blade.

As seen best by the full line showing in FIG. 2, the strike-off blade 32 has a leading edge 46 which overlies, in the raised position of the blade, a portion of the main blade support structure 19. In the retracted position of the door 27, the blade drops downwardly pivoting on the hinge 34 to a position as depicted in the phantom view in FIG. 2. The path taken by the leading edge 46 of the strike-off blade is going between the raised and lowered positions is one of the features of the preferred embodiment of the invention as will be brought out in the description of operation hereinafter. Most importantly, it should be noted that the cam blocks 40 and extensions 36 are not exposed on the outer side of the scraper walls thus effectively protecting these parts from damage by boulders and wear against the side walls of the cut.

With reference to FIG. 3, the door is moved in a known manner by links 31 attached at the rear. It is supported at the opposite ends below the floor portion 26 by rollers 28 traveling in the trackways 29 on the outboard side of the scraper walls 25. In the forward position of the door, the strike-off blade 32 is prevented from pivoting downwardly by the cam blocks 40 engaging the extensions 36 of the plates 35. As the door 27 commences to roller rearwardly for ejection of the earth material, the cam blocks 40, in cooperation with the extension 36, maintain the blade position until the leading edge 46 clears the back of the main blade support structure 19. It is important to note in the preferred embodiment that the downward arcuate travel of the blade does not commence until the hinge axis 34 is opposite the radius 45 of each cam block. Thus the leading edge 46 of the blade first moves in a straight path for a distance approximately equal to the distance traveled by the hinge axis 34 is moving to the end of the cam blocks 40 and then commences an arcuate downward motion as the hinge axis passes beyond the radii of the cam blocks.

In reverse, when the door is being closed and the I strike-off blade 27 is in the downwardly inclined position as shown in phantom view of FIG. 2, the extensions 36 first contact the cam blocks 40 causing the blade-t0 rotate in an are reaching its uppermost position 'in a movement which brings the leading edge 46 up behind I structure 19 thus, even though there is substantial wear of the cam surfaces 38-44, the structure 19 limits any drop of the blade and loss of earth material owing to cam wear is practically eliminated.

Further, in the preferred embodiment of the invention, it should be noted that as cam surfaces become worn, new cam sections 42 may be installed extending the life of the overall cam mechanism.

Instead of cam blocks, one may employ a fixed lug or stationary rollers on the inboard side of the scraper walls and instead of end plate extension 36, a similar means may be used on the blade to cause cam actuation. It is important, however, that the cam mechanism be wholly mounted inboard of the scraper side walls considering that it permits the strike-off blade to be shorter and inside the bowl. This means that the ends of the strike-off blade will be entirely behind the main blade structure and somewhat protected by it during the damp cycle. This also enables the front support roller 28 of the door to be placed farther forward than in a case where the cam actuation is outside of the side walls resulting in a more even distribution of weight on the door rollers 28. Thus, while I have described and illustrated herein a preferred embodiment of my invention as incorporated in a particular mechanism, it will be appreciated that modifications may be made therein and that other uses may be found. Therefore, it should be understood that I intend to cover by the appended claims all such modifications as fall within the spirit and scope of my invention.

I claim:

1. In an earth moving apparatus having an earth material receiving space, side and bottom wall members enclosing said space on at least three sides, a fixed blade mounted between the side wall members, the bottom wall member having a fixed portion and a movable portion shiftable for and aft below the fixed portion to uncover an opening for dumping earth material, a blade member hinged on the front of the movable portion pivoted between a first position in juxtaposed relation to the fixed blade and a second downwardly inclined position rearwardly of the fixed blade, said hinged blade member normally in the first position and assuming the second position when the movable portion is opened to permit dumping of the earth material, the improvement comprising a stationary cam means mounted adjacent the lower portion of and inboard of the side wall members and having a rectilinear camming surface, and a cam element pivoted with said hinged blade member and traveling therewith parallel to said side wall members so as to be engageable with said camming surface for causing the blade member to be actuated between the first and second positions during fore and aft movement, said camming surface and cam element cooperating to produce a rectilinear camming motion of the hinged blade element when in juxtaposed relation to the fixed blade.

2. The improvement according to claim 1 wherein the-cam means comprises a pair of cam blocks, one fixedly-positioned on the inner side of one side wall member and the other fixedly positioned diametrically opposite on the other side wall member, said camming surface located on each block and having a flat portion parallel to the bottom wall member and an arcuate portion at the rear, a pair of end members, one secured on one end of said blade member and the other secured on the opposite end, a said cam element located on each end member having a flat portion mutually slidable on the flat portion of said camming surfaces and being engageable with said arcuate portions to pivot the blade member between its first and second positions.

3. The improvement according to claim 2 wherein each cam block has a detachable lower section on which said camming surface is formed thereby to permit replacement when the camming surface becomes worn.

4. An earth moving apparatus having an earth material receiving space comprising a pair of said walls, a fixed bottom wall portion joining the side walls to the rear of said space, a movable bottom wall portion shiftable below the fixed bottom wall portion when dumping earth material, actuating means for moving the movable bottom wall portion between open and closed positions, a strike-off blade hinged on the front of the movable bottom wall portion, said blade pivoted between a first position level with said movable bottom wall portion in the closed position and a second downwardly inclined position when said wall portion is in the open position and acting in said second position to spread dumped earth material, a fixed main blade mounted between said side wall members, a support structure for said main blade, said strike-off blade overlying a portion of the support structure in its first position, a pair of cam blocks, one fixedly positioned on the inboard side of one side wall member and the other fixedly positioned diametrically opposite on the other side wall member, a pair of end members affixed to the opposite ends of said strike-off blade pivoted conjointly therewith, each end member having an upwardly and rearwardly extending portion parallel to the side wall members movable fore and aft with the strike-off blade in the path of said cam blocks and engageable therewith to actuate said strike-off blade between said first and second positions, each said cam block and end member having a flat camming surface mutually slidable relative to each other a distance at least equal to the displacement of said strike-off blade required to clear the support structure of said main blade whereby the strike-off blade has a stop limiting engagement with the main blade support structure should the camming surfaces become too worn.

5. A mobile earth handling apparatus according to claim 4 wherein each said cam block has a detachable cam section adapted to be replaced when the camming surface becomes too worn. 

1. In an earth moving apparatus having an earth material receiving space, side and bottom wall members enclosing said space on at least three sides, a fixed blade mounted between the side wall members, the bottom wall member having a fixed portion and a movable portion shiftable for and aft below the fixed portion to uncover an opening for dumping earth material, a blade member hinged on the front of the movable portion pivoted between a first position in juxtaposed relation to the fixed blade and a second downwardly inclined position rearwardly of the fixed blade, said hinged blade member normally in the first position and assuming the second position when the movable portion is opened to permit dumping of the earth material, the improvement comprising a stationary cam means mounted adjacent the lower portion of and inboard of the side wall members and having a rectilinear camming surface, and a cam element pivoted with said hinged blade member and traveling therewith parallel to said side wall members so as to be engageable with said camming surface for causing the blade member to be actuated between the first and second positions during fore and aft movement, said camming surface and cam element cooperating to produce a rectilinear camming motion of the hinged blade element when in juxtaposed relation to the fixed blade.
 2. The improvement according to claim 1 wherein the cam means comprises a pair of cam blocks, one fixedly positioned on the inner side of one side wall member and the other fixedly positioned diametrically opposite on the other side wall member, said camming surface located on each block and having a flat portion parallel to the bottom wall member and an arcuate portion at the rear, a pair of end members, one secured on one end of said blade member and the other secured on the opposite end, a said cam element located on each end member having a flat portion mutually slidable on the flat portion of said camming surfaces and being engageable with said arcuate portions to pivot the blade member between its first and second positions.
 3. The improvement according to claim 2 wherein each cam block has a detachable lower section on which said camming surface is formed thereby to permit replacement when the camming surface becomes worn.
 4. An earth moving apparatus having an earth material receiving space comprising a pair of said walls, a fixed bottom wall portion joining the side walls to the rear of said space, a movable bottom wall portion shiftable below the fixed bottom wall portion when dumping earth material, actuating means for moving the movable bottom wall portion between open and closed positions, a strike-off blade hinged on the front of the movable bottom wall portion, said blade pivoted between a first position level with said movable bottom wall portion in the closed position and a second downwardly inclined position when said wall portion is in the open position and acting in said second position to spread dumped earth material, a fixed main blade mounted between said side wall members, a support structure for said main blade, said strike-off blade overlying a portion of the support structure in its first position, a pair of cam blocks, one fixedly positioned on the inboard side of one side wall member and the other fixedly positioned diametrically opposite on the other side wall member, a pair of end members affixed to the opposite ends of said strike-off blade pivoted conjointly therewith, each end member having an upwardly and rearwardly extending portion parallel to the side wall members movable fore and aft with the strike-off blade in the path of said cam blocks and engageable therewith to actuate said strike-off blade between said first and second positions, each said cam block and end member having a flat camming surface mutually slidable relative to each other a distance at least equal to the displacement of said strike-off blade required to clear the support structure of said main blade whereby the strike-off blade has a stop limiting engagement with the main blade support structure should the camming surfaces become too worn.
 5. A mobile earth handling apparatus according to claim 4 wherein each said cam block has a detachable cam section adapted to be replaced when the camming surface becomes too worn. 